The invention relates to a method of characterizing video data which is characterized in a video data memory, preferably a linear data memory, by means of a characterizing code, preferably a time code, and to a video data memory in which such data are stored.
Video data memories that are known, for example video recorders, but also disk-based storage systems, usually characterize the video data by means of a characterizing code, usually a time code. This code characterizes each individual frame of the video data in an unequivocal manner. Each single frame can thus be reliably identified on the basis of the code. Increasingly, video data stored in such video data memories are to be processed further digitally. This is usually carried out in computer systems, for example also in personal computer systems. The problem then arises that the operating systems of such computer systems cannot work with the characterizing codes by means of which the video data is characterized in the video data memory, or are incapable of evaluating these codes.
Solutions have been proposed, this problem that eliminate by the video data being read out without characterizing codes from the video data memory and are buffered again in a further memory, for example the memory of a computer by means of which the data are further processed. The data are each provided with a new code in this buffer storage, i.e. a code which can be processed by the computer which is to process the data further. This procedure has the disadvantage that a buffer storage of the video data is required before this data can be further processed by a computer.
It is an object of the invention to provide a method of characterizing video data as well as a video data memory in which a buffer or intermediate storage of the video data is not necessary
According to the invention, this object is achieved in that the characterizing code is converted into a video data code in accordance with which the video data is arranged in video data files for the purpose of access to the video data by external units, the names of said video data files comprising at least parts of the respective associated characterizing codes, and in which the video data files are arranged in directories which contain at least parts of the respective associated characterizing codes.
The video data must be individually characterized so that external units, in particular computers, are capable of accurately accessing the video data. To achieve this, a characterizing code provided in the video data memory, which is usually a time code, is replaced with a new video data code. This conversion is effected only for external units; the characterizing code or time code continues to be used in the video data memory itself, since this is usually the only possibility in such an appliance. For external units, however, this code is converted into the video data code, which is so designed that it can be processed by the processing systems of the external units. As a result, the video data in the video data memory seem to be characterized, in the eyes of the external units, not by the characterizing code or time code, but by the video data code. The external units are capable of accurately accessing certain video data on the basis of the video data code.
The video data code is so designed in this case that the video data are arranged in video data files. Such files have a format which operating systems of connected computers are capable of reading. To identify the video data, the names of the video data files comprise portions which contain elements of the characterizing codes with which the video data are stored in the data memory. A cross-reference between the characterizing code and the video data code is thus always possible in the video data memory. The data files are arranged in directories which also contain elements of the characterizing codes. A file/directory system is thus created which can be read on the one hand by the external units, while on the other hand it is generated inside the video data memory from the characterizing code. A link between the video data code and the characterizing code is possible at all times as a result of the method of characterizing of the data files and directories.
In an embodiment of the invention, said method, in which a time code is used as the characterizing code, is characterized in that a file name is generated for the video data code for each partial frame of the digital picture signal, which name has the format DDHHMMSSFFLL.xxx, in which DD represents the day, HH the hour, MM the minute, SS the second, FF the full frame, and LL the partial frame values of the time code.
A time code is used in the characterizing codes which are most widely used in video data memories, such that each partial frame from a picture sequence of a digital picture signal is individually characterized. The time code then usually contains indications of the day, hour, minute, second, full frame, and partial frame values of the video data. An unequivocal characterization to below the frame level is made possible thereby. In the conversion of the characterizing code into the video data code according to the invention, the format of the latter, while readable to computers, can be so designed that it still contains elements of the time code. Thus an access to the corresponding values of the time code is also possible on the basis of the indications of the video data files in accordance with the video data code. The advantage remains, however, that the video data code is readable to external computers, i.e. to the operating systems thereof.
In a further embodiment of the invention, therefore, the data files in the video data code are arranged in a directory structure whose directory names comprise in downward hierarchical order day, hour, minute, second, full frame, and partial frame characteristics of the video data files.
Data files are usually arranged in a hierarchical directory structure in computer systems. This directory structure is utilized for the video data code such that higher-order directories or the names thereof contain, for example, elements of the day values of the time codes. In the next lower hierarchical level of the directory structure of the video data code, the directory names may advantageously comprise hour values. This is continued down to full frame or partial frame characteristics originating from the characterizing code, but converted into the directory structure of the video data code as elements of the directory names.
In a further embodiment of the invention, a computer connected to the network and capable of accessing the video data code is capable of changing the data file names provided in the video data code and/or of displacing data files provided in the video data code into other data file directories provided in the video data code, and an assignment table is created in this case, in which the changes are listed and in accordance with which the video data code for the relevant data files is made available in a changed form.
When the video data from the video data memory are read out and processed further by an externally connected computer on the basis of the video data code, there will often be a desire to change file names or to shift file names into other directories. This will always relate to the file names in accordance with the video data code, or the directory structure in accordance with this code. Since the characterizing code in the video data memory is a fixed item, it cannot be changed. A change of the characterizing codes in the video data memory is indeed not necessary in the method according to the invention, because the video data code is no more than a conversion of the characterizing code into an external code. Instead, therefore, an assignment table is made in which it is characterized which file names or directory names were changed by an external unit in the video data code. The name in accordance with this assignment table is subsequently issued as the video data code for these file names or directory names. This new video data code thus replaces that video data code which is normally derived from the characterizing code with which the data are stored in the video data memory.
A change of the video data code as regards file name changes or directory name changes is thus possible for external units, without the unchangeability of the characterizing code having any negative influence thereon.
The object defined above in relation to a video data memory, in which video data characterized by a characterizing code, preferably a time code, are preferably linearly stored, is achieved in that means for generating a video data code from the characterizing code are provided, which means transmit the video data code, in accordance with which video data code the video data are arranged in video data files, to external units, the names of said files comprising at least parts of the relevant associated characterizing codes, and in accordance with which video data code the video data files are arranged in directories which contain at least parts of the relevant associated characterizing codes.
Means for generating a video data code are provided in the video data memory. These means calculate the video data code from the characterizing code. This video data code is provided to external units instead of the characterizing code and characterizes the individual video data in an unequivocal manner.
The means accordingly serve to convert the characterizing code into the video data code, and vice versa. The video data code then is designed in the manner described above.
In a further embodiment of the invention in relation to the video data memory, it is provided that external units, especially those connected via a network, are capable of accessing the video data code and of changing file names provided in the video data code and/or shifting data files provided in the video data code into other file directories provided in the video data code, that the means for generating the video data code in this case make an assignment table in which the changes are listed, and that the means for generating the video data code provide the video data code for the relevant data files in a form changed in accordance with the assignment table.
If externally connected computers accessing the video data code change file names and/or directory names of this code, the means for generating the video data code will make an assignment table. It is indicated therein which new file names and/or directory names replace the original file names and/or directory names. A change in the characterizing code is not necessary as a result of this. When the video data code is subsequently made available, the changes in accordance with the assignment table are taken into account, so that file names and/or directory names were apparently actually changed, as seen by external units. In fact, the changes of the file names and/or directory names in accordance with the assignment table were taken into account only in the conversion of the characterizing code into the video data code.